1. Field of the Invention
The present invention relates to a method for controlling conveyance speed of a sheet, a method for manufacturing a wearing article, an apparatus for manufacturing a wearing article, and a wearing article.
2. Description of the Related Art
A wearing article, such as a diaper or a sanitary napkin, is produced by laminating a plurality of continuous sheets formed of a nonwoven fabric, a film or the like, and subjecting the laminate to a given processing. For example, the processing includes placement of a member, such as an absorbent body or a tape onto a given area of a continuous sheet, and printing or ink application to form a graphic, pattern or the like for improving appearance, on a given area of a continuous sheet. In advance of laminating the continuous sheet subjected to such a processing to another continuous sheet, it is necessary that these continuous sheets are positionally adjusted, i.e., registered, with respect to each other.
JP 2001-517098, JP 2000-502649 and JP 2002-512566 disclose a control and a method for registering two continuous sheets. Specifically, JP 2001-517098, JP 2000-502649 and JP 2002-512566 disclose a technique for registering a first layer having a plurality of components, and a second layer having a plurality of reference marks, wherein, when one of the reference marks is out of position with respect to an associated one of the components, a speed of the first or second layer is adjusted.
However, the technique disclosed in JP 2001-517098, JP 2000-502649 and JP 2002-512566 is not premised on cutting the continuous sheets at a position adequate for the reference mark and the associated component. Specifically, JP 2001-517098, JP 2000-502649 and JP 2002-512566 do not disclose means for suppressing a misregistration between a target cutting position and an actual cutting position, which would otherwise occur in response to stretching and contraction of the continuous sheet. Therefore, in cases where an absorbent body, a tape or a pattern (hereinafter referred to as “processing component”) is provided on a continuous sheet, a position of the processing component with respect to a cutting position (edge) of the continuous sheet will vary in each wearing article after the cutting, which makes it impossible to accurately produce wearing articles.